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A Scale and Rotation Invariant Approach to Tracking Human Body Part Regions in Videos. Yihang Bo. Hao Jiang. Institute of Automation, CAS Boston College. Boston College. Challenges. Previous Rectangular Part Methods. Templates with Different scales . Templates with
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A Scale and Rotation Invariant Approach to Tracking Human Body Part Regions in Videos Yihang Bo Hao Jiang Institute of Automation, CAS Boston College Boston College
Previous Rectangular Part Methods Templates with Different scales Templates with Different rotations If the target scale and rotation are unknown, local part extraction becomes a very slow process.
Overview of the Method • We track human body part regions (arm, leg and torso) in videos. • Our model considers spatial and temporal coupling among parts. • It is invariant to scale and rotation.
The Non-tree Model Body part coupling between two successive video frames
Part Region Candidates Superpixels Object class independent Region Proposals P.F. Felzenszwalb and D.P. Huttenlocher, Efficient Graph-Based Image Segmentation International Journal of Computer Vision, Volume 59, Number 2, September 2004. Ian Endres, and Derek Hoiem, “Category Independent Object Proposals”, ECCV 2010.
3D Superpixels Video segmentation (3D superpixels) usually do not directly give human part regions.
Partial Background Removal (Optional) warping warping warping warping … …
Criteria Relative Ratio Shape Matching Part Distance Part Overlap Shape Changes Position Changes Appearance Changes
Overlap Region Overlap Region Overlap
Size Ratio Part Size Ratio
Shape Consistency Across Frames Shape Consistency
Motion Smoothness Motion Continuity
Color Consistency Appearance Consistency
Inference on a Loopy Graph … We assign region candidates to each of the body part node so that the objective function is minimized.
Convert to a Chain … … Linear meta-graph
Convert to a Chain … … Unfortunately, there are too many whole body configurations in each video frame.
Convert to a Chain … … Solution: we find the best-N whole body configurations in each video frame.
Find Best-N Body Configurations on a Cycle Best-N (with torso1) + Best-N (with torso2) Best-N (with torso1,2) + Best-N (with torso3) Best-N (with torso1,2,3) … + Best-N (with torso M) Best-N (with torso1..M)
Region Tracking on a Trellis Best-N Body configurations Frame 1 Frame 2 Frame k
Sample Results on Five Test Videos V1 V2 V3 V4 V5
Comparison Result [N-best] D. Park, D. Ramanan. "N-Best Maximal Decoders for Part Models”, ICCV 2011.
Comparison Result Quantitative results
Conclusion • By tracking body part regions, we can achieve efficient scale and rotation invariant human pose tracking. • This method can be used for human tracking in complex sports videos.